Conventionally, external devices such as clinician and patient programmers communicate with an implantable medical device (IMD) through a near field form of communication such as an inductive coupling. Due to the short range of the inductive coupling, a telemetry head is placed in close proximity to the IMD to establish the inductive link. Because the telemetry head has a very short range and consequently is in such close proximity to the IMD, there is essentially no risk of inadvertently communicating with a different nearby IMD.
Far field communication has become an alternative to the use of near field links between external devices and implantable medical devices. Far field communication uses frequencies that allow for electromagnetic signal propagation over significantly larger distances than the maximum distance of near field links. This increased range of signals allows an external device to communicate with the IMD without placing a telemetry head in close proximity to the IMD. However, the increased range of the far field communication creates issues that are not a concern for near field links.
In particular, far field communication by the external device creates the possibility that other IMDs besides the intended IMD are in communication range of the external device. Therefore, the external device must either have advance knowledge of an identifier of the desired IMD or the external device must receive a user selection from a list of IMDs that respond to a discovery signal by the external device. Requiring the user to select the proper IMD from a list adds extra time and burden to the process and also presents an opportunity for human error where the user may select the wrong device and/or application for an intended device.